This invention is directed to open-end spinning, and more particularly to an improvement in the thread delivery system which guides the thread initially formed in the fiber collecting groove of the spinning rotor of an open-end spinning machine therethrough to a pickup mechanism. In accordance with the invention an improved roughing and bulking effect on the yarn, as well as better control over the exiting yarn, is obtained.
Open-end spinning is a fiber preparation technique which originated in Europe and has received widespread acceptance in the last twenty - twenty-five years. Open-end spinning is a distinctly faster operation than other yarn preparation techniques such as "ring" spinning; however, it has several disadvantages. One disadvantage is that it is difficult to eliminate yarn breakages or "ends down." Another disadvantage is that open-end spinning techniques generally do not result in a yarn having a "soft" hand. Threads produced in openend spinning rotors exhibit less hairy or fuzzy texture and have less bulk. In the case of knitted and woven apparel goods, a soft hand is required. As a result yarns intended for certain knitted and woven apparel fabrics have not achieved widespread acceptance from open-end spinning systems.
For these and other reasons, it has been previously attempted to obtain a softer hand and eliminate ends down situations by introducing one or more obstacles in the path of the yarn as it leaves the spinning rotor through the delivery tube. At such times the spinning rotor causes the yarn to rotate around the inner periphery of the delivery tube as it passes therethrough engaging such obstacles as it rotates. This results in some surface treatment of the yarn. Such approaches are illustrated in U.S. Pat. Nos. 4,258,541 to Le Chatelier et al; 4,011,712 to Egbers et al; and 4,516,397 to Raasch et al.
While such approaches have resulted in improvements to the hand softness and have resulted in some elimination of ends down situations, there remain certain unsolved problems. For example, the number of ends down is still higher than desired. The resulting yarn tends to shed as a result of encountering the aforesaid obstacles. It is very difficult and expensive to obtain yarns having extremely soft hand or varying degrees of softness from one yarn type to another yarn type. Also, the resulting yarns tend to lack uniformity along their length in that there are rough spots (thick and thin places) in the resulting yarn.
With this in mind, the present invention is an attempt to provide a superior yarn (1) by improving the interior configuration of the navel member leading to the yarn delivery tube, and (2) by altering the manner in which the aforesaid navel member is constructed. In general, in accordance with the present invention there is provided a cylindrical yarn treating insert which is formed separately, but then fixed in the barrel portion of the navel member. The navel member, as used herein, is defined as the member generally mounted in the rotor cover into which the yarn initially passes as it leaves the yarn collection surface of the rotor and through which the yarn passes as it proceeds to the yarn delivery tube and/or take-up mechanism.
In the approach of the present invention a navel yarn treating insert is fabricated separately, then fixed in the barrel portion of the navel member. The aforementioned insert includes a longitudinal channel passing centrally therethrough, and the inner wall is provided with a plurality of peripherally spaced grooves therein. Each groove receives a ceramic rod therein, and a portion of the periphery of such rods is embedded in the aforementioned channel to provide a pattern of obstructions to the yarn as it passes therethrough. The depth of the grooves may be changed or altered by design from insert to insert, which results in the rods being embedded to a greater or lesser extent. This naturally results in a greater or lesser offset between the rods which determines the degree of roughness in the yarns passing therethrough, as well as allowing for some compensation for differences in yarn size.
The above-described insert is formed separately from the ceramic throat piece, which throat piece is embedded in the front surface of the navel member. Separation of the fabrication of the throat piece and insert results in manufacturing economies. All throat pieces may be formed of the same dimension, yet are compatible with inserts having differing interior rod configurations. Thus, in the manufacture of the navel members a single size and shape of housing may be formed, a single size of ceramic throat piece may be molded, yet easily combined with several insert/rod configurations.
It has been found that the navel members formed in accordance with the present invention result in fewer ends down situations, minimize yarn shedding, provide yarn with a very soft hand where desired, and results in a more uniform yarn diameter throughout the length. Further, by merely varying the distance between the rods varying types of yarn softness characteristics may be achieved.
It is therefore an object of the present invention to provide a unique and improved construction for the navel member of open-end spinning frames.
It is another object of the present invention to provide a navel member of the type described which results in a softer hand and a higher quality thread output.